diff --git a/package.json b/package.json
index 7560d40941..9d613091b6 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
   },
   "devDependencies": {
     "@babel/core": "^7.2.0",
-    "@polkadot/dev": "^0.22.11",
+    "@polkadot/dev": "^0.22.12",
     "@polkadot/ts": "^0.1.43"
   }
 }
diff --git a/packages/types/src/Digest.ts b/packages/types/src/Digest.ts
index 61a58a2d1c..b764dd6c59 100644
--- a/packages/types/src/Digest.ts
+++ b/packages/types/src/Digest.ts
@@ -72,12 +72,12 @@ export class Seal extends Tuple {
 export class DigestItem extends EnumType<AuthoritiesChange | ChangesTrieRoot | Other
   | Seal> {
   constructor (value: any) {
-    super([
+    super({
       Other, // Position 0, as per Rust (encoding control)
       AuthoritiesChange,
       ChangesTrieRoot,
       Seal
-    ], value);
+    }, value);
   }
 }
 
diff --git a/packages/types/src/EventRecord.ts b/packages/types/src/EventRecord.ts
index 93ab1725d5..aca46c05a3 100644
--- a/packages/types/src/EventRecord.ts
+++ b/packages/types/src/EventRecord.ts
@@ -31,10 +31,10 @@ export class Finalization extends Null {
  */
 export class Phase extends EnumType<ApplyExtrinsic | Finalization> {
   constructor (value: any, index?: number) {
-    super([
+    super({
       ApplyExtrinsic,
       Finalization
-    ], value, index);
+    }, value, index);
   }
 }
 
diff --git a/packages/types/src/ExtrinsicStatus.ts b/packages/types/src/ExtrinsicStatus.ts
index 8e47dd3ace..3b7d63a131 100644
--- a/packages/types/src/ExtrinsicStatus.ts
+++ b/packages/types/src/ExtrinsicStatus.ts
@@ -47,11 +47,11 @@ export class Usurped extends Hash {
  */
 export default class ExtrinsicStatus extends EnumType<Finalised | Usurped | Broadcast | Dropped> {
   constructor (value: any, index?: number) {
-    super([
+    super({
       Finalised,
       Usurped,
       Broadcast,
       Dropped
-    ], value, index);
+    }, value, index);
   }
 }
diff --git a/packages/types/src/Metadata/Modules.ts b/packages/types/src/Metadata/Modules.ts
index 09617719f5..53c89dd1ad 100644
--- a/packages/types/src/Metadata/Modules.ts
+++ b/packages/types/src/Metadata/Modules.ts
@@ -152,10 +152,10 @@ export class StorageFunctionType$Map extends Struct {
 
 export class StorageFunctionType extends EnumType<Type | StorageFunctionType$Map> {
   constructor (value?: any, index?: number) {
-    super([
+    super({
       Type,
       StorageFunctionType$Map
-    ], value, index);
+    }, value, index);
   }
 
   /**
diff --git a/packages/types/src/MisbehaviorReport.ts b/packages/types/src/MisbehaviorReport.ts
index 2db77b788f..34c5b62600 100644
--- a/packages/types/src/MisbehaviorReport.ts
+++ b/packages/types/src/MisbehaviorReport.ts
@@ -120,12 +120,12 @@ export class BftDoubleCommit extends BftAtReport {
  */
 export class MisbehaviorKind extends EnumType<BftProposeOutOfTurn | BftDoublePropose | BftDoublePrepare | BftDoubleCommit> {
   constructor (value?: BftAtReportValue | Uint8Array, index?: number) {
-    super([
+    super({
       BftProposeOutOfTurn,
       BftDoublePropose,
       BftDoublePrepare,
       BftDoubleCommit
-    ], value, index);
+    }, value, index);
   }
 }
 
diff --git a/packages/types/src/codec/EnumType.spec.js b/packages/types/src/codec/EnumType.spec.ts
similarity index 53%
rename from packages/types/src/codec/EnumType.spec.js
rename to packages/types/src/codec/EnumType.spec.ts
index 99db405465..f9d7d96f3f 100644
--- a/packages/types/src/codec/EnumType.spec.js
+++ b/packages/types/src/codec/EnumType.spec.ts
@@ -7,25 +7,46 @@ import Text from '../Text';
 import U32 from '../U32';
 
 describe('Struct', () => {
-  it('provides a clean toString() (raw)', () => {
+  it('provides a clean toString() (value)', () => {
     expect(
       new EnumType(
-        [Text, U32],
+        { Text, U32 },
         new Uint8Array([0, 2 << 2, 49, 50])
-      ).raw.toString()
+      ).value.toString()
     ).toEqual('12');
   });
 
   it('provides a clean toString() (enum)', () => {
     expect(
       new EnumType(
-        [Text, U32],
+        { Text, U32 },
         new Uint8Array([1, 2 << 2, 49, 50])
       ).toString()
     ).toEqual('U32');
   });
 
-  it('allows checking against defined indexes', () => {
+  it('decodes from a JSON input (lowercase)', () => {
+    expect(
+      new EnumType(
+        { Text, U32 },
+        { 'text': 'some text value' }
+      ).value.toString()
+    ).toEqual('some text value');
+  });
+
+  it('decodes from a JSON input (mixed case)', () => {
+    expect(
+      new EnumType(
+        { Text, U32 },
+        { 'U32': 42 }
+      ).value.toString()
+    ).toEqual('42');
+  });
+
+  // We are currently not using this approach, none of the types in Substrate currently
+  // have any overrides. Insteda of trying to support it (just-in-case), rather have it
+  // removed to simplyfy the code - it can be pulled-back if needed
+  it.skip('allows checking against defined indexes', () => {
     expect(
       new EnumType(
         { 1: Text, 5: U32 },
@@ -37,7 +58,7 @@ describe('Struct', () => {
   it('allows accessing the type and value', () => {
     const text = new Text('foo');
     const enumType = new EnumType(
-      [Text, U32],
+      { Text, U32 },
       { Text: text }
     );
 
diff --git a/packages/types/src/codec/EnumType.ts b/packages/types/src/codec/EnumType.ts
index 01100f8cf2..fd0690aecc 100644
--- a/packages/types/src/codec/EnumType.ts
+++ b/packages/types/src/codec/EnumType.ts
@@ -2,16 +2,20 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { isNumber, isObject, isU8a, isUndefined, u8aConcat, u8aToHex } from '@polkadot/util';
+import { assert, isNumber, isObject, isU8a, u8aConcat, u8aToHex } from '@polkadot/util';
 
 import Base from './Base';
 import Null from '../Null';
 import { Codec, Constructor } from '../types';
 
-type TypesArray = Array<Constructor>;
 type TypesDef = {
-  [index: number]: Constructor
-} | TypesArray;
+  [name: string]: Constructor
+};
+
+type Decoded = {
+  index: number,
+  value: Codec
+};
 
 /**
  * @name EnumType
@@ -23,62 +27,61 @@ type TypesDef = {
 //   - As per Enum, actually use TS enum
 //   - It should rather probably extend Enum instead of copying code
 export default class EnumType<T> extends Base<Codec> implements Codec {
-  private _Types: TypesArray;
+  private _def: TypesDef;
   private _index: number;
   private _indexes: Array<number>;
 
   constructor (def: TypesDef, value?: any, index?: number | EnumType<T>) {
     const decoded = EnumType.decodeEnumType(def, value, index);
 
-    super(
-      decoded.value
-    );
-
-    this._Types = Array.isArray(def)
-      ? def
-      : Object.values(def);
-    this._indexes = Object.keys(def).map((index) =>
-      parseInt(index, 10)
-    );
+    super(decoded.value);
 
+    this._def = def;
+    this._indexes = Object.keys(def).map((_, index) => index);
     this._index = this._indexes.indexOf(decoded.index) || 0;
   }
 
-  static decodeEnumType<T> (def: TypesDef, value?: any, index?: number | EnumType<T>): { index: number, value: any } {
+  private static decodeEnumType<T> (def: TypesDef, value?: any, index?: number | EnumType<T>): Decoded {
     // If `index` is set, we parse it.
     if (index instanceof EnumType) {
-      return { index: index._index, value: new def[index._index](index.raw) };
+      return EnumType.createValue(def, index._index, index.raw);
     } else if (isNumber(index)) {
-      return { index, value: new def[index](value) };
+      return EnumType.createValue(def, index, value);
     }
 
     // Or else, we just look at `value`
-    if (isU8a(value)) {
-      return { index: value[0], value: new def[value[0]](value.subarray(1)) };
-    } else if (isNumber(value) && !isUndefined(def[value])) {
-      return { index: value, value: new def[value]() };
+    return EnumType.decodeViaValue(def, value);
+  }
+
+  private static decodeViaValue (def: TypesDef, value?: any): Decoded {
+    if (value instanceof EnumType) {
+      return EnumType.createValue(def, value._index, value.raw);
+    } else if (isU8a(value)) {
+      return EnumType.createValue(def, value[0], value.subarray(1));
+    } else if (isNumber(value)) {
+      return EnumType.createValue(def, value);
     } else if (isObject(value)) {
       // JSON comes in the form of { "<type (lowercased)>": "<value for type>" }, here we
       // additionally force to lower to ensure forward compat
       const key = Object.keys(value)[0];
       const lowerKey = key.toLowerCase();
-      const index = Object
-        .keys(def)
-        .find((k) => def[+k].name.toLowerCase() === lowerKey);
+      const keys = Object.keys(def).map((k) => k.toLowerCase());
+      const index = keys.indexOf(lowerKey);
 
-      if (isUndefined(index)) {
-        const message = 'Unable to reliably map input on JSON';
+      assert(index !== -1, 'Unable to reliably map input on JSON');
 
-        console.error(message, value, def);
-
-        throw new Error(message);
-      }
-
-      return { index: +index, value: new def[+index](value[key]) };
+      return EnumType.createValue(def, index, value[key]);
     }
 
-    // Worst-case scenario, return this
-    return { index: 0, value: new (Object.values(def)[0])() };
+    // Worst-case scenario, return the first with default
+    return EnumType.createValue(def, 0);
+  }
+
+  private static createValue (def: TypesDef, index: number, value?: any): Decoded {
+    return {
+      index,
+      value: new (Object.values(def)[index])(value)
+    };
   }
 
   /**
@@ -106,7 +109,7 @@ export default class EnumType<T> extends Base<Codec> implements Codec {
    * @description The name of the type this enum value represents
    */
   get type (): string {
-    return this._Types[this._index].name;
+    return Object.keys(this._def)[this._index];
   }
 
   /**
diff --git a/yarn.lock b/yarn.lock
index 557f6f7738..401b94b3de 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1327,10 +1327,10 @@
   resolved "https://registry.yarnpkg.com/@nodelib/fs.stat/-/fs.stat-1.1.2.tgz#54c5a964462be3d4d78af631363c18d6fa91ac26"
   integrity sha512-yprFYuno9FtNsSHVlSWd+nRlmGoAbqbeCwOryP6sC/zoCjhpArcRMYp19EvpSUSizJAlsXEwJv+wcWS9XaXdMw==
 
-"@polkadot/dev@^0.22.11":
-  version "0.22.11"
-  resolved "https://registry.yarnpkg.com/@polkadot/dev/-/dev-0.22.11.tgz#fcacaba21cb7f72490ad67e228171ce6cf5903f7"
-  integrity sha512-xYyAknjwqNZqDpxNgbH137R5m3jACQjnJi7/rz3uR8GFW107rFb7sGTtvtX3TYaS7CP69Eiy+mCRCE+3bdKHsw==
+"@polkadot/dev@^0.22.12":
+  version "0.22.12"
+  resolved "https://registry.yarnpkg.com/@polkadot/dev/-/dev-0.22.12.tgz#f0eaf211efb3d6b70869dab63a022858a110de85"
+  integrity sha512-dF4LJHrDOLbn7AqBm2ZL8o9YqUsm0+00OED8XCI0n2jy7jvMd37PwPn3gib0Ip7xwSZiikJbHvNkvmyGUUZjpw==
   dependencies:
     "@babel/cli" "^7.2.0"
     "@babel/core" "^7.2.0"